Embodied energy in buildings : wood versus concrete - reply to Börjesson and Gustavsson

We analyse the wood and concrete designs of the Wälludden building described by Börjesson et al. (Energy Policy 28 (2000) 575) in terms of their embodied energy, employing an environmentally extended input–output framework in a tiered hybrid life-cycle assessment, and in a structural path analysis. We illustrate the complexity of the inter-industry supply chains underlying the upstream energy requirements for the building options, and demonstrate that higher-order inputs are difficult to capture in a conventional process analysis. Our calculations show that Börjesson and Gustavsson's estimates of energy requirements and greenhouse gas emissions are underestimated by a factor of about 2, and that corresponding greenhouse gas balances are positive at about 30 t C-eq. Nevertheless, Börjesson and Gustavsson's general result—the concrete-framed building causing higher emissions—still holds.

Net Energy Analysis of Double Glazing for Residential Buildings in Temperate Climates

Energy used in buildings is a major contributor to Australia’s energy consumption and associated environmental impacts. The advent of complex glazing systems such as double glazing, particularly in northern America and Europe, has partially closed a weak thermal link in the building envelope. In milder climates, however, building envelope features may not be as effective in life cycle energy terms, i.e. including the embodied energy of their manufacture. A net energy analysis compares the savings in operational energy to the additional requirements for embodied energy, in terms of the energy payback period and energy return on investment. The effectiveness of double glazing is determined for an Australian residential building. A wide range of building operation regimes was simulated. These results support the principle of installing double glazing in residential buildings in Melbourne, Australia, at least in terms of net primary energy savings.

The business case for incorporating sustainability in office buildings : the adaptive reuse of existing buildings

The effect of climate change and global warming has received increased attention in society with constant reminders about the importance of energy efficiency and sustainability in buildings. Whilst the focus is often placed on smaller items such as plastic bags, air conditioners and motor vehicles, the emphasis has recently shifted to structures in the built environment. Office buildings have been identified as contributing significantly to global warming during their building lifecycle with a substantial contribution to CO2 omissions. In response, building designs and construction techniques have evolved over time to improve energy efficiency and reduce CO2 omissions. Whilst property valuers, managers and analysts must remain up-to-date regarding changes, relatively little research has been conducted about whether and how increased sustainability, such as signified in a Green Star rating affects a property’s highest and best value and long-term lifecycle. This study investigates the degree to which sustainability is understood in the property marketplace, especially in relation to property values with the emphasis placed on a cost- benefit analysis from both an owner’s and tenant’s perspective. Whilst it may be argued that incorporating sustainability into a new office building is cost prohibitive on a financial cost-benefit analysis, often various minor steps can be taken to upgrade the sustainability of an existing building. This project examines recent trends in capital expenditure to increase the sustainability of offices and where Green Star ratings have been applied to establish whether any corresponding increase in value is evident. In order to develop a researchframework, a thorough literature review will be conducted of recent Australian and overseas studies. This will enable links between sustainability and office buildings to be highlighted, and vitally how they affect a property’s value in both the short and long-term.

User satisfaction in sustainable office buildings : a preliminary study

Energy efficiency was first mandated for commercial buildings in 2006 in Part J of The Building Code of Australia (BCA) and regulators are already implementing increased measures in 2010 (ABCB 2010). Further increases will follow as part of the co-ordinated effort to reduce building related greenhouse gas emissions. The introduction of the Energy Efficiency Disclosure Bill 2010 will establish a national scheme to promote the disclosure of information about the energy efficiency of office buildings as well as further highlighting the need for efficiency. Increased energy efficiency in the form of insulation, energy efficient light fittings, sophisticated Building Management Systems (BMS), micro-generation such as solar and wind turbines all result in measurable quantifiable reductions in operating costs for owners and tenants. However convincing all building owners about the sound business case for adopting sustainability measures has not been fully realised. To-date the adoption of cutting edge sustainable buildings in Australia is restricted to a few industry leaders, such as Investa and ISPT in Victoria for example. Sustainable building owners and tenants often benefit from reduced operating costs during the building lifecycle although the ‘intangible’ effect on businesses (e.g. employee productivity) is uncertain. This aspect has not been accurately quantified and has not been included as part of the measurement of sustainability in buildings.

This study will allow property stakeholders, including government policy-makers and investors/developers, to better understand the optimal type and level of sustainability to be incorporated into the built environment. In addition this knowledge will enable policymakers to make more informed decisions with regards to the likely impact of the legislative measures they propose in respect of sustainability and buildings in The Building Code of Australia (BCA) and other relevant legislation.

Emerging technologies in building envelopes

Advancements in engineering and space technology are increasingly finding application in buildings. Building envelopes are utilising components of high-technological solutions resulting in better visibility, greater light transmission, increased energy generation and storage capacity, improved shading and ventilation and integration with the external environment. This report summarises several technological advancements and suggests forthcoming directions for building envelope design. Many of the technologies presented here have been invented and developed in Australia, yet are not commonly used by the building construction industry.

An assessment of the energy and water embodied in commercial building construction

Growing global concern regarding the rapid rate at which humans are consuming the earth’s precious natural resources is leading to greater emphasis on more effective means of providing for our current and future needs. Energy and fresh water are the most crucial of these basic human needs. The energy and water required in the operation of buildings is fairly well known. Much less is known about the energy and water embodied in construction materials and products. It has been suggested that embodied energy typically represents 20 times the annual operational energy of current Australian buildings. Studies have suggested that the water embodied in buildings may be just as significant as that of energy. As for embodied energy, these studies have been based on traditional analysis methods, such as process and input-output analysis. These methods have been shown to suffer from errors relating to the availability of data and its reliability. Hybrid methods have been developed in an attempt to provide a more reliable assessment of the embodied energy and water associated with the construction of buildings. This paper evaluates the energy and water resources embodied in a commercial office building using a hybrid analysis method based on input-output data. It was found that the use of this hybrid analysis method increases the reliability and completeness of an embodied energy and water analysis of a typical commercial building by 45% and 64% respectively, over traditional analysis methods. The embodied energy and water associated with building construction is significant and thus represents an area where considerable energy and water savings are possible over the building life-cycle. These findings suggest that current best-practice methods of embodied energy and water analysis are sufficiently accurate for most typical applications, but this is heavily dependent upon data quality and availability.

Realising air leakage in Australian housing

Air tightness of Australian buildings is a great unknown. Despite testing methods being developed and implemented in many advanced European and North American countries, this has not happened in Australia. This paper notes energy efficiency gains that can be achieved through tighter construction, and follows on from the investigation into testing methodology and literature discussed in TEC 23: Air Leakage in Buildings – Review of International Literature and Standards. Several domestic case studies are used to implement two accepted testing methods and aid to build the case for increased awareness of airtight housing in Australia.

A development of environmental conscious design of prison buildings

Environmental conscious design refers to variety of approaches in architecture design that covers technical, behavioural, and functional aspects (Goulding et al, 1992). These approaches usually include contradictory measures with social indicators (Sykes, 1995; Norton, 1999). The contradiction is magnified in incarceration architecture, which is very specific type of buildings (McConville, 2000). Prison buildings represent the split between the society requirements and the needs for the users, in this case the prisoners, to have comfortable environment. Energy as an ultimate natural resource reflects both the cost to the society, in terms of cooling/ heating load and the need for comfort and rehabilitation of prisoners (Al-Hosany and Elkadi, 2000). Different energy codes tend to control the thermal behaviour of buildings in certain environment in order to maximise their energy efficiency (e.g. CIBSE, 1999). In prison buildings, some of the main variables of such code are not relevant. While energy codes, for example, regulate the use of glass in buildings by either minimise the openings size (prescriptive criteria) or by determine an overall limit of heat transfer (performance criteria), the objective in prison buildings is to minimise glass areas for security purposes. This leads in turn to reduction in visual and comfort levels in prison cells. The aim of this paper is to address the balance between the society requirements of reducing energy consumption in prison buildings and the need for humane and comfortable environment for prisoners in order to maintain sustainability. The paper investigates the possible role of façade technologies to bridge the gap between requirements of both society and prisoners.

Building energy efficiency labeling programme in Singapore

The use of electricity in buildings constitutes around 16% of Singapore's energy demand. In view of the fact that Singapore is an urban city with no rural base, which depends heavily on air-conditioning to cool its buildings all year round, the survival as a nation depends on its ability to excel economically. To incorporate energy efficiency measures is one of the key missions to ensure that the economy is sustainable. The recently launched building energy efficiency labelling programme is such an initiative. Buildings whose energy performance are among the nation's top 25% and maintain a healthy and productive indoor environment as well as uphold a minimum performance for different systems can qualify to attain the Energy Smart Office Label. Detailed methodologies of the labelling process as well as the performance standards are elaborated. The main strengths of this system namely a rigorous benchmarking database and an independent audit conducted by a private accredited Energy Service Company (ESCO) are highlighted. A few buildings were awarded the Energy Smart Office Label during the launching of the programme conducted in December 2005. The labeling of other types of buildings like hotels, schools, hospitals, etc. is ongoing.

Practitioner perceptions of sustainability in the Building Code of Australia

Buildings have a significant impact on environmental quality, resource use, human health and productivity. One definition of sustainable building is that which meets current building needs and reduces impacts on future generations by integrating building materials and methods that promote environmental quality, economic vitality, and social benefit’ (City of Seattle, 2006). In response to a changing view of
sustainability the Building Code of Australia (BCA) adopted energy measures in 2005 to residential buildings and, in 2006, to Class 1 – 9 buildings. In many respects the measures represented a watershed for the Australian Building Regulations which had not included sustainability within the BCA. The goals of the BCA are to enable the achievement and maintenance of acceptable standards of structural sufficiency, safety (including safety from fire), health and amenity for the benefit of the community now and in the future (ABCB, 2004a). As with any change some Building Surveyors and construction practitioners viewed these measures with apprehension. How would the measures be assessed? Furthermore, was the BCA the appropriate place for these measures and was this a broadening of the scope of the building regulations beyond
its traditional remit of health and life safety in buildings? This research used a questionnaire survey the canvass the views and perceptions of Building Surveyors and Architects with regards to sustainability and the BCA in 2006.

Ecology and conservation of insectivorous bats in rural landscapes

Throughout the world, the increasing use of land for agriculture has been associated with extensive loss and fragmentation of natural habitats and, frequently, the degradation of remaining habitats. The effects of such habitat changes have been well studied for some faunal groups, but little is known of their consequences for bats. The aim of this study was to investigate the ecology and conservation of an assemblage of insectivorous bats in a rural landscape, with particular focus on their foraging and roosting requirements. This increased knowledge will, hopefully, assist the formulation of policy and management decisions to ensure the long-term survival of bats in these altered environments. The distribution and abundance of insectivorous bats in the Northern Plains of Victoria was investigated to determine the impacts of land-use change and to identify factors influencing the distribution of bats in rural landscapes. Thirteen species of insectivorous bats were recorded across the region by sampling at 184 sites. Two species were rare, but the remaining 11 species were widespread and occurred in all types of remnant wooded vegetation, ranging from large blocks (≥200 ha) to small isolated remnants (≤5 ha) and scattered trees in cleared farm paddocks. There was no significant difference between remnant types in the relative abundance of bat species, in species richness, or in the composition of bat assemblages at study sites. In a subsequent study, no difference in the activity levels of bats was found between remnants with different tree densities, ranging from densely-vegetated blocks to single paddock trees. However, sites in open paddocks devoid of trees differed significantly from all types of wooded remnants and had significantly lower levels of bat activity and a different species composition. In highly cleared and modified landscapes, all native vegetation has value to bats, even the smallest remnant, roadside and single paddock tree. Roost sites are a key habitat requirement for bats and may be a limiting resource in highly modified environments. Two species, the lesser long-eared bat Nyctophilus geoffroyi and Gould's wattled bat Chalinolobus gouldii, were investigated as a basis for understanding the capacity of bats to survive in agricultural landscapes. These species have different wing morphologies, which may be influential in how they use the landscape, and anecdotal evidence suggested differences in their roosting ecology. Roosting ecology was examined using radio-tracking to locate 376 roosts in two study areas with contrasting tree cover in northern Victoria. Both species were highly selective in the location of their roosts in the landscape, in roost-site selection and in roosting behaviour, and responded differently to differing levels of availability of roosts. The Barmah-Picola study area incorporated remnant vegetation in farmland and an adjacent extensive floodplain forest (Barmah forest). Male N. geojfroyi roosted predominantly within 3 km of their foraging areas in remnants in farmland. However, most female N. geoffroyi, and both sexes of C. gouldii, roosted in Barmah forest up to 12 km from their foraging areas in farmland remnants. These distances were greater than previously recorded for these species and further than predicted by wing morphology. In contrast, in the second study area (Naring) where only small remnants of wooded vegetation remain in farmland, individuals of both species moved significantly shorter distances between roost sites and foraging areas. There were marked inter- and intra-specific differences in the roosts selected. C. gouldii used similar types of roosts in both areas - predominantly dead spouts in large, live trees. N. geoffroyi used a broader range of roost types, especially in the farmland environment. Roosts were typically under bark and in fissures, with males in particular also using anthropogenic structures. A strong preference was shown by both sexes for roosts in dead trees, and entrance dimensions of roosts were consistently narrow (2.5 cm). In Barmah forest, maternity roosts used by N. geoffroyi were predominantly in narrow fissures in large-diameter, dead trees, while at Naring maternity roosts were also found under bark, in buildings, and in small-diameter, live and dead trees. The number of roost trees that are required for an individual or colony is influenced by the frequency with which bats move between roosts, the proportion of roosts that are re-used, the distance between consecutive roosts, and the size of roosting colonies. Both species roosted in small colonies and regularly shifted roost sites within a discrete roost area. These behavioural traits suggest that a high density of roost sites is required. There were marked differences in these aspects of behaviour between individuals roosting in Barmah forest and in the fragmented rural landscape. At Naring, N. geqffroyi remained in roosts for longer periods and moved greater distances between consecutive roosts than in Barmah forest. In contrast, C. gouldii used a smaller pool of roosts in the farmland environment by re-using roosts more frequently. Within Barmah forest, there is an extensive area of forest but the density of hollow-bearing trees is reduced due to timber harvesting and silvicultural practices. Individuals were selective in the location of their roosting areas, with both species selecting parts of the forest that contained higher densities of their preferred roost trees than was generally available in the forest. In contrast, in farmland at Naring, where there were small pockets of remnant vegetation with high densities of potential roost sites surrounded by cleared paddocks with few roosting opportunities, little selection was shown. This suggests that in Barmah forest the density of trees with potential roosts is lower than optimal, while in farmland roosting resources may be adequate in woodland remnants, but limiting at the landscape scale since more than 95% of the landscape now provides no roosting opportunities. Insectivorous bats appear to be less severely affected than some other faunal groups by habitat fragmentation and land-use change. A highly developed capacity for flight, the spatial scale at which they move and their ability to cross open areas means that they can regularly move among multiple landscape elements, rather than depend on single remnants for all their resources. In addition, bats forage and roost mainly at elevated levels in trees and so are less sensitive to degradation of wooded habitats at ground level. Although seemingly resilient to habitat fragmentation, insectivorous bats are fundamentally dependent on trees for roosting and foraging, and so are vulnerable to habitat loss and ongoing rural tree decline. Protection of the remaining large old trees and measures to ensure regeneration to provide ongoing replacement of hollow-bearing trees through time are critical to ensure the long-term conservation of bats in rural landscapes.

The potential to reduce the embodied energy in construction through the use of renewable materials

The threat of dangerous levels of global warming demand that we significantly reduce carbon emissions over the coming decades. Globally, carbon emissions from all energy end-uses in buildings in 2004 were estimated to be 8.6 Gt CO2 or almost one quarter of total CO2 emissions (IPCC 2007). In Australia, nearly ten per cent of greenhouse gases come from the residential sector (DCCEE 2012). However, it is not merely the operation of the buildings that contributes to their CO2 emissions, but the energy used over their entire life cycle. Research has demonstrated that the embodied energy of the construction materials used in a building can sometimes equal the operational energy over the building’s entire lifetime (Crawford 2011). Therefore the materials used in construction need to be carefully considered. Conventional building materials not only represent high levels of embodied energy but also use resources that are finite and are being depleted. Renewable building materials are those materials that can be regenerated quickly enough to remove the threat of depletion and in theory their production could be carbon-neutral. To assess the potential for renewable building materials to reduce the embodied energy content of residential construction, the embodied energy of a small residential building has been determined. Wherever possible, the conventional construction materials were then replaced by commercially-available renewable building materials. The embodied energy of the building was then recalculated. The analysis showed that the embodied energy of the building could be reduced from 7.5 GJ per m2 to 5.4 GJ per m2 i.e. by 28%. The commercial availability of renewable materials, however, was a limiting factor and indicated that the industry is not yet well positioned to embrace this strategy to reduce embodied energy of construction. While some conventional building materials could readily be replaced, in many instances a renewable substitute could not be found.